Benchmarking Components for Photoelectrochemical Water-Splitting Devices

Objective evaluation of solar energy conversion  efficiencies is of fundamental importance to  the development of solar energy driven photoelectrochemical (PEC) water-splitting devices.  Unfortunately there is no current standard methodology for evaluating the efficiency of fuel-forming PEC components and devices.  Consequently, in the literature, there is a wide array of testing procedures and calculations being used to report device and component efficiency.  Here we will highlight some of the common testing procedures and  efficiency calculations being used, pointing out important areas where there is no universal agreement.  In addition, we will present the testing procedure used within the Benchmarking facility of the Joint Center for Artificial Photosynthesis (JCAP).  We illustrate our procedure by presenting pertinent photoelectrochemical data collected from measurements taken on well-known PEC water-splitting components and devices (e.g. Pt/p-Si, Ni/BVO, triple junction Si, p-GaP, p-InP, n-TiO₂)  and explain how this data can be translated into real world device-pertinent figures-of-merit.